Question

我正在将ViewController插入到当前堆栈中。并试图像这样执行popviewcontroller。

 var viewControllersArray: [UIViewController] = self.navigationController!.viewControllers


    if(dm.isLoginViewLoaded)
    {
        print("Login view already loaded")

    }

    else
    {
        print("Login view havent load before")
        let myviewcontroller:LoginViewController=UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LOGIN") as! LoginViewController
        let index=viewControllersArray.count-2
        viewControllersArray.insert(myviewcontroller, at: index)
        // update navigationController viewControllers
        self.navigationController!.setViewControllers(viewControllersArray, animated:false)

    }
    self.navigationController?.popViewController(animated: true)

但为什么我无法实现我想做的事情。即使在满足我的viewcontroller的第二个条件下总是推送到Root viewcontroller。我想在我当前的视图控制器和根视图控制器之间添加一个新的viewcontroller，并执行pop操作。请帮我。感谢

Answer 1

试试这段代码：

let arrController:[UIViewController] = (self.navigationController?.viewControllers)!//array of all controllers in navigation stack
    for vc in arrController
    {
      if (type(of: vc)  == type(of: LoginViewController
))//check exist or not
      {
        self.navigationController?.popToViewController((arrController[(arrController.index(of: vc))!]), animated: true)
      }
    }

Answer 2

我认为你只是“错误地计算”阵列位置。你的索引应该是：

let index = viewControllersArray.count - 1   // *not* -2

然而，这可能是一种更“强大”的方法：

@IBAction func popToLogin(_ sender: Any) {

    if let navVC = self.navigationController {

        var bFoundLogin = false

        var viewControllersArray = navVC.viewControllers

        for vc in viewControllersArray.reversed() {
            if vc is LoginViewController {
                // we found LoginViewController in stack, so
                //  pop to it (even if it's multiple levels back)
                bFoundLogin = true
                navVC.popToViewController(vc, animated: true)
                // found it, so break out of the for loop
                break
            }
        }

        if !bFoundLogin {

            // we didn't find LoginViewController in stack, so
            //  replace current VC with LoginVC

            //if let loginVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LOGIN") as? LoginViewController {
            if let loginVC = UIStoryboard(name: "AnimConstraints", bundle: nil).instantiateViewController(withIdentifier: "LOGIN") as? LoginViewController {

                // insert loginVC before last item
                viewControllersArray.insert(loginVC, at: viewControllersArray.count - 1)
                // set the NavVC's array of controllers
                navVC.setViewControllers(viewControllersArray, animated: false)
                // pop back one level (to our inserted loginVC)
                navVC.popViewController(animated: true)

            }

        }

    }

}

使用循环来“查找”堆栈中的LoginViewController，即使它不是“下一个在线”，也可以“弹出”它，也不需要你的dm.isLoginViewLoaded跟踪（除非您在其他地方使用它）。

将新的viewcontroller添加到当前堆栈

2 个答案: